Course talk:CPSC522/Principal Component Analysis

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Critique #2003:13, 8 February 2020
Critique022:43, 6 February 2020

Critique #2

I should emphasize in advance that having worked with PCAs extensively, I may not the best eye for catching unclear steps. I found the page a great read overall. There is a tendency of repetition (such as re-iterating the overview of PCA during abstract, motivation and overview) which in my opinion is fine and probably re-enforces learning. The notation was a bit unclear at the beginning especially with d+1 since PCA is an unsupervised algorithm where you don't really need a label Y, to perform it effectively (that said, there are variations that factor Y in explicitly). Updating the notation to discussing such variations may potentially aid in improving the page. However, all said, it's an excellent foundational page on PCA, that's clear, reasonably concise and covers the topic well.

Marking at this stage would be (roughly): The topic is relevant for the course. 5 The writing is clear and the English is good. 5 The page is written at an appropriate level for CPSC 522 students (where the students have diverse backgrounds). 5 The formalism (definitions, mathematics) was well chosen to make the page easier to understand. 4 The abstract is a concise and clear summary. 5 There were appropriate (original) examples that helped make the topic clear. 5 There was appropriate use of (pseudo-) code. 4.5 (steps are sufficient, but maybe adding pseudo-code could help) It had a good coverage of representations, semantics, inference and learning (as appropriate for the topic). 5 It is correct. 5 It was neither too short nor too long for the topic. 5 It was an appropriate unit for a page (it shouldn't be split into different topics or merged with another page). 5 It links to appropriate other pages in the wiki. 3 (you could definitely link more pages on "builds on" and "related" sections.) The references and links to external pages are well chosen. 4 I would recommend this page to someone who wanted to find out about the topic. 5 This page should be highlighted as an exemplary page for others to emulate. 5 If I was grading it out of 20, I would give it: 18.5

PeymanBateni (talk)03:12, 8 February 2020

Here are some suggestions and comments that I have for your page:

provide links from the builds on topics?

did the motivation not have any source?

there is a repeat of introduction of the PC - in motivation and in overview again

maybe combine steps 2,3,4 since 3 is not always used and they are describing the same process "step 2 - form matrix Z by centering features of X and maybe even standarizing"

maybe have the eigendecomposition as another numbered step?

it is not clear from step 7 how we can limit/choose the number of the PC's to use - seems like we are projecting all of them always?

you have good flow and structure of the page and great example with the data! I thought it was easy to read and to follow, short and to the point.

The topic is relevant for the course. 5 The writing is clear and the English is good. 5 The page is written at an appropriate level for CPSC 522 students. 5 The formalism (definitions, mathematics) was well chosen to make the page easier to understand. 5 The abstract is a concise and clear summary. 5 There were appropriate (original) examples that helped make the topic clear. 5 There was appropriate use of (pseudo-) code. - (no pseudo-code but not sure if it is really needed?) It had a good coverage of representations, semantics, inference and learning (as appropriate for the topic). 4 It is correct. 5 It was too short for the topic (i.e., 1 means too long, 3 means about right) 4 It was an appropriate unit for a page (it shouldn't be split into different topics or merged with another page). 5 It links to appropriate other pages in the wiki. 4 The references and links to external pages are well chosen. 4 I would recommend this page to someone who wanted to find out about the topic. 5 This page should be highlighted as an exemplary page for others to emulate. 4 If I was grading it out of 20, I would give it: 18

SvetlanaSodol (talk)22:43, 6 February 2020